Assembly and a method for intervention of a subsea well

ABSTRACT

A well assembly for intervention of a subsea well or a well head with a wireline or a coiled tubing connected to a tool or a toolstring and including lubricator and an injector package. The injector package is adapted to inject the wireline or coiled tubing into the well or well head. The lubricator is adapted to be fitted in a lubricator package and define a locking chamber via which the wireline or coiled tubing is to be forwarded to the well or well head. The lubricator is adapted to be connected to the well head. The injector package includes an injector module adapted to be fitted to the well head. The injector module is adapted to forward the lubricator through it when the packages are connected to each other and to the well head, for the purpose of injecting the wireline or coiled tubing into the well or well head. The lubricator includes a lubricator pipe element and an associated moveable stripper/packer element adapted to be connected to a well barrier module on the well head.

TECHNICAL FIELD

The present invention relates to an assembly for intervention of asubsea well or a well head by means of a wireline or a coiled tubingconnected to a tool assembly. The well assembly comprises lubricatormeans and an injector package. The injector package is adapted to injectthe wireline or coiled tubing into the well or well head.

The invention also relates to a method for injecting a wireline orcoiled tubing into a subsea well or well head.

The term “well head” shall be interpreted in a broad meaning, andinclude all equipment normally associated to a subsea well head, such asChristmas tree, tubing hanger, production flowbase (if any) etc. and allequipment associated thereto.

By coiled tubing is meant a continuous and flexible tubing. Said tubingis preferably made of a metallic material or a corresponding material,such as composites.

BACKGROUND OF THE INVENTION

Subsea wells need maintenance and inspection activities at a regularbasis. Such activities can be carried out by means of tools delivered tothe well via a wire or coiled tubing that extends from a floating vesselor a platform down into the well. Typical maintenance and inspectionactivities in the well are measurements and monitoring of wellconditions, perforating, gravel packing, production stimulation andrepair of a downhole completion or production tubing. Today's systemsnormally use a so-called riser tube, which extends from the vessel tothe top of the well head, via which the wire or coiled tubing is feddown into the well. Such systems require restriction of movementsbetween the vessel and the well head due to the configuration of theriser tube. Thereby, the use of such systems becomes difficult,time-consuming and costly.

As an alternative there has been proposed subsea systems that do not usea riser tube for feeding the coiled tubing down to the well, but let thecoiled tubing run freely between the vessel and the well head by meansof a so-called riserless system. In for example the U.S. Pat. No.4,899,823 to Cobb et al. there is disclosed such a system, which isprovided with a coiled tubing injector for injecting the coiled tubinginto the well through the well head and a blow out preventer stack withassociated equipment (well pressure barrier section) between theinjector and the well head.

The system according to said US-patent is also provided with coiledtubing stripper elements and a well fluid stuffing box carried by theinjector via which the coiled tubing is injected into the well head. Theblow out preventer stack and the stuffing box may here mainly be Cconsidered to function as a lubricator assembly or lubricator means. Thewell pressure barrier section facilitates the connecting of the coiledtubing to the well head with regard taken to the fluid pressure in thewell. Prior to lowering the injector down to the well head the coiledtubing is latched in the injector and preferably also positioned in thestuffing box.

For lowering and retrieval of the injector and the well barrier section,there are provided guide wires that extend from the vessel to the wellhead. When it is desired to retrieve the injector, it is first operatedto withdraw the coiled tubing from the well head. The tubing is lockedto the drive chains of the injector and lifted up to the vessel. As theinjector is bulky this means that a rather large weight has to beretrieved just for the purpose of withdrawal of the coiledtubing/toolstring to the vessel. This is impractical and thus costly, inparticular as multiple toolstrings are commonly used to accomplish theoperation objectives.

THE OBJECT OF THE INVENTION

It is an object of the present invention to provide an assembly and amethod for intervention of a subsea well or well head that promote anuncomplicated way of handling a coiled tubing or wireline used fordelivering tools to the well or well head. The invention shall reducethe costs and the time consumed for handling the coiled tubing, inparticular the rig up/rig down time necessary to deploy/retract thecoiled tubing/toolstring.

SUMMARY OF THE INVENTION

The object of the invention is achieved by means of the initiallydefined assembly, characterised in that said lubricator or enclosuremeans is adapted to be fitted in a lubricator package and define alocking chamber via which said wireline or coiled tubing is to beforwarded to the well or well head; said lubricator means being adaptedto be connected to said well head; said injector package, comprising aninjector module, being adapted to be fitted to said well head, and thatthe injector module is adapted to forward said lubricator means throughit, when said packages are connected to each other and to the well head,for the purpose of injecting said wireline or coiled tubing into thewell or well head.

According to a preferred embodiment of the present invention the wellassembly further comprises a well barrier package. The lubricatorpackage is adapted to be fitted onto said injector package; saidinjector package is adapted to be fitted onto said well barrier package,and said well barrier package is adapted to be fitted onto said wellhead. The injector module is thus adapted to forward said lubricatormeans through it, when the lubricator, injector and the well barrierpackage are connected to each other respectively and to the well head.

The injector module is preferably designed to allow for the passage ofthe lubricator or enclosure means through it The lubricator means isthen used as a pressure locking chamber when the coiledtubing/toolstring is running into or out of the wellhead or well throughthe injector module. The lubricator means is preferably mainlytube-shaped, thereby being easier to forward through the injectormodule. When the coiled tubing/toolstring is to be injected into thewell head or well, the lubricator means is forwarded through theinjector module and connected to a well barrier module or package at alower position below the injector module in order to function as apressure locking chamber. Preferably, at least a part of the length ofthe lubricator means is forwarded through the injector module,sufficient for it to be connected to the well barrier module or package.The coiled tubing/toolstring is then run down into the well head orwell. After the coiled tubing/toolstring has been run down, thelubricator means is retracted to an upper position above the injectormodule, and the coiled tubing/toolstring is injected into the well bymeans of the injector module. The coiled tubing is adapted for deliveryof one or more tools to the well or well head, said tools being usede.g. for maintenance or repair work therein. When the coiledtubing/toolstring is to be run out of the well head or well thelubricator means is again forwarded through the injector module from itsupper position and connected to the well barrier module in order tofunction as a pressure locking chamber. Thereby, the coiled tubing ispreferably being run down or out of the well head or well through thelubricator means.

The coiled tubing/toolstring is preferably rigged up with the upper partof the lubricator package without the need to retract or lift-off theinjector package. Thus, the injector package, which is bulky and heavy,does not need to be rigged up together with the coiledtubing/toolstring.

The movement of the lubricator means between the upper position abovethe injector module and the lower position below the injector module ispreferably accomplished by a hydraulic cylinder, or a hydraulicallyoperated screw device.

According to one embodiment of the invention, the well barrier packagecomprises an upper well barrier module arranged below the injectorpackage, said upper well barrier module preferably being a part of theinjector package. According to another embodiment of the invention, thewell barrier package also comprises a lower well barrier module orpackage, which is preferably separately arranged below the upper wellbarrier package and connected, via a well tree or a Christmas treeadapter package whenever applicable, to the well head.

The inventive assembly comprises a remote-controlled coupling device,preferably arranged in the interface section between the lubricatorpackage and the injector package, for connecting/disconnecting thelubricator means to/from its upper position, i.e. above the injectormodule/package, and a corresponding coupling device, preferably arrangedbetween the injector module and the well barrier module/package,especially the upper well barrier module, for connecting/ disconnectingthe lubricator means to/from its lower position, i.e. below the injectormodule/package.

The injector module preferably comprises at least two driving elementsbetween which the lubricator means is forwarded/retracted and by meansof and between which the coiled tubing, after the retraction of thelubricator means through the injector module to its upper position abovethe injector module, is injected into the well head or well. The spacingbetween said driving elements is adjustable so as to engage the drivingelements and the coiled tubing in order to inject the coiledtubing/toolstring during the injecting operation of the injector module.Preferably, said driving elements are extended in the axial direction ofthe injector package/module, and arranged opposite each other. The twodriving elements are preferably fitted to the framework of the injectorpackage by a sliding arrangement so that they can be operated sidewaysby hydraulic or electric power to leave room for the lubricator means aswell as to engage the coiled tubing for the purpose of injecting thecoiled tubing/toolstring into the well head or well during the injectingoperation of the injector module.

The lubricator or enclosure means preferably comprises a lubricator pipeelement, a fixed stripper/packer element that is arranged in the upperpart or end of the lubricator pipe element, and an associated moveablestripper/packer element. The moveable stripper/packer element is adaptedto feed and retract the coiled tubing together with the tool assembly ortoolstring through the lubricator pipe when the lubricator pipepreferably is in its lower position, i.e. connected to the well barriermodule/package. Each of said element is preferably sealingly arrangedaround the coiled tubing and between itself and the lubricator pipeelement

The moveable stripper/packer element preferably remains in place at andlocked to the coupling device of the well barrier module while thelubricator pipe element is retracted to said upper position in order tohold the coiled tubing in a fixed position before it is to be injectedby means of the injector module.

The inventive assembly is based on operation from a floating vessel atthe sea surface, preferably a dynamically positioned light interventionvessel or a drilling oil rig/ship, and is designed to operate a wirelineor coiled tubing on vertical or horizontal Christmas trees. For thelubricator to be adapted to operate a wireline instead of a coiledtubing, the upper part of the lubricator package including stripperelements is replaced with a wireline sealing device, preferably astuffing box. Thus, the conversion from coiled tubing to wirelineoperation and vice versa may easily be performed. Accordingly, thecombination of wireline and coiled tubing operation is also within thescope of the present invention, which makes it possible to cover themajority of all required intervention tasks.

The floating vessel comprises means including a surface injector, whichis heave compensated, and an associated coiled tubing reel for feedingout the coiled tubing from the vessel and for retracting the same to thevessel. The coiled tubing is freely extending in the water with atension defined by the system between the surface injector and theinjector module. The slack of the coiled tubing and the tension thereonis controlled and maintained by the surface injector and associatedreeling mechanism means on the coiled tubing reel. However, there shouldpreferably be provided guide wires extending from the vessel to the wellhead for the purpose of guiding the modules/packages of the assemblyduring deployment and retrieval thereof. In addition, especially atlarge depths, a running tool is preferably used.

The floating vessel, injector package and the wireline or coiled tubingextending between them preferably form a passive system that permitssubstantial movement of the vessel in relation to the well head.

The object of the invention is also achieved by means of the initiallydefined method for injecting a wireline or coiled tubing into a subseawell or well head, comprising the steps of: connecting an injectorpackage, having an injector module for injecting the wireline or coiledtubing into the well or wellhead, to the well head; forwardinglubricator means adapted to be fitted in a lubricator package, throughthe injector module when said packages are connected to each other andto the well head; connecting said lubricator means defining a lockingchamber via which the coiled tubing is forwarded to the well or wellhead, to the well head; and injecting said wireline or coiled tubing bymeans of the injector module into the well or well head. According to apreferred embodiment of the inventive method a well barrier package isfurther connected onto the well head; the injector package is connectedonto the well barrier package; the lubricator package is connected ontothe injector package; and that the lubricator means is forwarded throughthe injector module when said packages are connected to each other andto the well head.

The coiled tubing is connected to a toolstring or tool assembly in orderto deliver one or more tools to the well or well head for maintenanceand/or repair work therein.

The lubricator means is thus preferably forwarded/retracted via anopening in the injector module to the well barrier package. In apreferred embodiment of the present invention, the coiled tubing isforwarded through a lubricator pipe element of the lubricator means whenit has been forwarded through the injector module and connected to thewell barrier package/module. The coiled tubing/toolstring is thusforwarded through said connected lubricator pipe element, and connectedto the well barrier package or generally to the well head. Thelubricator pipe element can be moved through the injector module withoutany need of disconnecting the injector package from the well head.

After the coiled tubing/toolstring has been run into the well thelubricator pipe element is disconnected and retracted through theinjection module such that it is displaced in relation thereto, enablingthe injector module to grip the coiled tubing by means of drivingelements and commence injecting the coiled tubing/toolstring into thewell The lubricator pipe element is here preferably retracted to anupper position above the injector module.

The injector is also used for retracting the coiled tubing/toolstringfrom the well. Before the tubing is disconnected from the well head thelubricator pipe element is forwarded from its retracted position andonce again connected to well barrier package in order to operate as alocking chamber. After retracting the toolstring into the lubricatorpreferably by means of the above mentioned surface injector of thefloating vessel, and closing the well barrier module (deployment valve)located below the injector module, the lubricator pipe element isflushed or cleaned from possible well fluids and contamination etc. thathas entered into it during the operation, and then run to its upperposition. The toolstring is then preferably retracted with the top partof the lubricator package.

The coiled tubing and the lubricator package may either be removed asone single unit or separately from the injector package connected viathe well barrier package to the well head.

The coiled tubing is arranged with a constant tension or a tensiondefined by the system, extending from the surface injector of thefloating vessel to the injector module or the well head.

Wires or the like are arranged between the vessel and the well head orthe different packages/modules of the well assembly, i.e. the injectorpackage/module, the lubricator package and the well barrierpackage/module for guiding them in order to fit the separatepackages/modules to each other onto the well head. The coiled tubing mayalso be guided by means of said wires.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained more closely by the followingdetailed description of different preferred embodiments thereof withreference to the appended drawings, on which:

FIG. 1 is a schematic view of a system for intervention of a subsea wellincluding a dynamically positioned intervention vessel and an assemblyaccording to the invention,

FIG. 2 is an exploded schematic view of the inventive assembly,connected to a subsea Christmas tree, according to one embodiment of theinvention,

FIG. 3 is a partly cut side-view of a part of the embodiment accordingto FIG. 2, including a so-called coiled tubing lubricator package and aninjector package,

FIG. 4 is a side-view of a part of the coiled tubing lubricator packageaccording to another embodiment of the invention (corresponding to FIG.1),

FIG. 5 is an exploded cross section of a top part of the lubricatorpackage of FIG. 4 for receiving a tool assembly connected to a coiledtubing,

FIGS. 6 a-6 f are schematic side views showing the main steps beingperform in order to injected the coiled tubing/tool assembly into thewell head according to the inventive method.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a system for intervention of a subsea production wellincluding a dynamically positioned light intervention vessel 1 and anassembly according to a preferred embodiment of the invention. Theassembly 2 is connected via a Christmas tree adapter package to theChristmas tree of the well head 4 located at the seabed, and comprises acoiled tubing injector package 5, a coiled tubing lubricator package 6and a well pressure barrier package 11. The lubricator package 6comprises a lubricator or an enclosure means defining a pressure lockingchamber through which a coiled tubing 7 is to be forwarded to the wellhead as will be explained more in detail below. The lubricator package6, the injector package 5 and the well barrier package 11 of the wellassembly are adapted to and arranged onto each other respectively. Thecoiled tubing 7 is adapted for delivery of one or more tools to the well3, said tool(s) being used for maintenance and repair work therein. Thewell assembly is also connected to an umbilical or control cable 8extending from a reel on the vessel to the well assembly 2 for thesupply of electrical and hydraulic power, chemical fluids, and fortransmission of electrical signals needed during the interventionoperation.

The vessel 1 is equipped with a derrick with sufficient height andstrength to handle the different packages. The derrick will have guidewire winches with constant tension and a lifting winch with acompensation arrangement for handling the packages. The vessel is alsoprovided with a surface injector 38 adapted to be arranged in thederrick, and an associated coiled tubing reel 39 for feeding out thecoiled tubing 7 from the vessel and for retracting the same to thevessel.

FIG. 2 shows an exploded schematic view of the assembly 2 according toone embodiment of the invention, whereby the assembly comprises a lowerwell pressure barrier package 11 a, an injector package 5 (including anupper well pressure barrier module 11 b), and a lubricator package 6.During assembling of the packages, each package is lowered down from thevessel towards the seabed, landed on top of each other and firmlyconnected both structural and functional to the Christmas tree/wellheadin the order as shown in FIG. 2. One or more packages may alternativelybe assembled together at the surface on the vessel before lowering themdown.

For the above purpose, guiding wires are used extending, preferablythrough guide funnels or the like of the frameworks of the packages,between the wellhead and the vessel. At large depths a running tool isused instead or in addition. The Christmas tree is of a usual type wellknown by the skilled person and, therefore, not further discussed here.The barrier package 11 a, comprises in general blow out preventer (BOP)stack, arranged below the injector module/package, and includes a numberof valves, and a control pod with all electric/electronic functions tooperate the complete subsea system during the intervention operation.The control umbilical 8, which can be remotely connected/disconnected,is here connected to the pod. The blow out preventer stack shouldpreferably, in addition to its valves, be provided by means for variousforms of well circulation (e.g. during production stimulation of thewell) by connecting passages or bypasses such as hoses or risers to thestack, whereby possible pressure increase in the well may be controlled.The well barrier package 11 has the same function and type of equipmentas a lower workover riser package (LRP) of a conventional system.Furthermore, there are hydraulic and electric couplers (not shown)between the Christmas tree and the well barrier package making itpossible to control the functions of the Christmas tree and downholesafety valve during intervention.

As shown in more detail in the embodiment according to FIG. 2, theinjector package 5 comprises a separate, self-standing injector module12 adapted for the purpose of passing the lubricator through it as wellas, during the injecting operation of the injector module, injecting thecoiled tubing 7 into the well 3, and the upper well pressure barriermodule 1 lb. The lubricator package 6 comprises a tubular body in theform of a lubricator pipe element 13 (surrounded by a protection casingas indicated in the figure) with an upper end 16, and a mechanical screwdevice 15 for the purpose of passing the lubricator pipe element 13through the injector module 12.

As shown in FIG. 3, the injector module 12 comprises at least twoopposed driving elements 17, 18. extending in the axial direction ofsaid module, between which the lubricator pipe element 13 isforwarded/retracted. The driving elements are fitted to the framework ofthe injector module by a sliding arrangement so that they can beoperated sideways by hydraulic or electric power to leave room for thelubricator pipe as well as to engage with the coiled tubing. In thisway, the spacing between said driving elements 17, 18 may be adjustableto allow for lubricator pipes or tubes with varying dimensions to passthrough the injector module 12 with or preferably without engagement tothe driving elements 17, 18. According to one embodiment of theinvention, the diving elements 17, 18 include endless bands or beltsarranged on rotating wheels or shafts 19 driven by hydraulic or electricmotors/gears (not shown). Instead of endless bands or belts any othersuitable arrangement may be used. For example, rotating wheels or shaftsmay be arranged to be in direct engagement with the coiled tubing 7.Further, for example, each of the driving elements may have coiledtubing grippers connected to an endless chain that is driven by ahydraulic or electric motor/gear. A hydraulic force thereby givesfriction between the coiled tubing and the grippers in order toaccomplish the injection of the coiled tubing/toolstring into the wellduring the injecting operation of the injector module. The top andbottom of the driving elements have a guiding arrangement to guide thecoiled tubing into the grippers when the driving elements are operatedtowards each other. The framework of the injector module is resting onload cells, as indicated in FIG. 3, connected to the main fame of theinjector package for measurement of the coiled tubing push and pullforce.

When the lubricator pipe is to be passed or forwarded through theinjector module 12, the driving elements 17, 18 are operated sideways toan outer position, the lubricator pipe element 13 is run down throughthe module 12, and entered into the coupling device 21, here in the formof a multiconnector, to establish i. a. connection/disconncetion to theupper well barrier package 11 b and the well head 4. After pressurecontrolling, testing of various seals and opening of appropriate valves(gate valve, ball valve etc.) of the well barrier package and well head,the injecting operation is started in order to inject the coiledtubing/toolstring to the well 3.

According to a preferred embodiment of the invention the lubricator pipeelement 13 is forwarded through the injector module 12 by means of adedicated screw device 15 including guiding rods and jacking screw(s).The screw device 15 is arranged inside the framework of the lubricatorpackage 6.

The assembly is provided with remote-controlled coupling devices 20, 21preferably arranged at the interface sections of the lubricator/injectorpackage and the injector/upper well barrier package respectively. Inparticular, the coupling device 20 (only partly shown in FIG. 3) is amulticonnector arranged in the interface section between the injectorpackage 5 and the lubricator package 6, and has a hydraulic coupler toconnect/disconnect the lubricator package to/from the injector package,and hydraulic and electric couplers for all the functions on thelubricator package, such as connecting/disconnecting and sealing thelubricator pipe element 13 in its upper position above the injectormodule. The coupling device or multiconnector 21, comprises a lower andan upper part. The lower part has a large hydraulic operated coupler toconnect/disconnect, seal and lock the injector package 5 to the wellbarrier package (blow out preventer stack 22) and in the same operationpreferably connect all hydraulic and electric functions between thesetwo packages. The upper part of the multiconnector 21 has twohydraulically operated couplers, one coupler to connect/disconnect, sealand lock the lubricator pipe element to the multiconnector 21 duringforwarding/retraction of tools, and the other to connect/disconnect,seal and lock a main stripper/packer element 30 (see FIG. 5) to themulticonnector 21 during coiled tubing operation. In addition, the upperpart of the multiconnector 21 also includes a hydraulically operatedmechanism for activating the main stripper element 30.

From the above it should be understood that the lubricator pipe elementcomprises a connector device, which is preferably remote-controlled andarranged at its lower end for connecting the lubricator pipe element 13to the corresponding coupling device, i.e. the multiconnector 21 seatedon the stripper BOP stack 22 of the upper well barrier package 11 b, andfor disconnecting the lubricator pipe 13 from said multiconnector 21.

FIG. 4 separately shows another preferred embodiment of the lubricatorpackage 6, which is connected to the injector package 5 and via thecoupling device 21 of the injector package to the lower well barrierpackage 11 a. The generally tubular body of the lubricator pipe element13 is displaceable in relation to its framework 23 (including guidefunnels 24 etc.) in a direction to/from the injector module 12 of theinjector package 5. The lubricator pipe element 13 can be displaced soas to be forwarded/retracted through the injector module 12 down to thecoupling device 21 arranged on the top of the stripper BOP stack 22 ofthe upper well barrier package 11 b. At the lower part of the lubricatorpackage 6, a hydraulic cylinder device 25 is fixedly attached to theframework of the lubricator package 6 through which the lubricator pipeelement 13 extends via sealed ends of the cylinder device 25. Thelubricator pipe element 13 has a ring-shaped piston or an annular flange27, the outer periphery of which generally corresponds to the innerperiphery of the cylinder device 25. Thereby, the inner periphery of thecylinder element 25, said flange and the outer periphery of thelubricator pipe element 13 delimit a space 26. The lubricator package 6preferably comprises means (not shown) for supplying a pressure medium,such as a hydraulic fluid, into the space 26 and removing the same fromthe space 26 in order to move the piston 27 and thereby the lubricatorpipe element 13 in relation to the injector module 12. By means of thehydraulic cylinder device 25 it is also possible to move the coiledtubing 7 to and from engagement with the injector module 12. Themechanical screw device 27 (as indicated in FIG. 3) forforwarding/retracting the lubricator pipe element 13 to engage with thecoupling device 21 of the upper well barrier package 11 a will hereserve as primary or back up so as to allow for the pressure medium toact as described above. The length of the lubricator pipe element may beabout 15 m, which is typically a standard length. It may be made up ofone piece of pipe or a number of pipes. The diameter of the lubricatorpipe may preferably be of a standard dimension, such as 179 mm and 187mm, enabling receipt of standard types of tools being used duringintervention. Further, as should be understood, the length of thelubricator pipe element to be forwarded/retracted through the injectormodule 12 is adapted for connection/disconnection to/from the couplingdevice 21 and depends on the axial dimension (height) of the injectormodule/package. A typical length in a preferred embodiment is about 5 m.

FIG. 5 is an exploded view and shows an embodiment of the upper part orend 16 of the lubricator package 6. The lubricator package has a topfunnel 28 enabling the coiled tubing/toolstring to be easily introducedtherein. A stationary or fixed stripper/packer element 29 is connectedto the bottom of the guide funnel 28 and is sealingly engaged theretoand around the lubricator pipe 13 and the coiled tubing 7, which extendsthrough the guide funnel 28 and the fixed stripper/packer element 29.Accordingly, the fixed stripper/packer element 29 seals the lubricatorpipe 13 at its upper end, when the pipe 13 is pressurised, during in andout pressure lockage of tools through the well barrier package 11 andvalve tree 9. The upper part of the lubricator package 6 also comprisesa second moveable stripper/packer element 30 for deployment into astripper bowl (not shown), and a coiled tubing connector 31 forconnecting the coiled tubing 7 to the toolstring 32 that is to beintroduced into the well head/well. The moveable stripper/packer element30 is the main seal element during the intervention operation. Thisstripper/packer element 30 is inserted, preferably on the floatingvessel, into the lubricator pipe together with the toolstring and sealsaround the coiled tubing and between itself and the lubricator pipe 13,thereby it prevents well fluid to leak out to the sea water. Themoveable stripper/packer element 30 is used for running thetool/toolstring down 32 through the lubricator pipe 13.

Thus, the lubricator means comprises a lubricator pipe 13, a fixedstripper/packer element 29, and the associated moveable stripper/packerelement 30, and works as a pressure locking chamber for passing thecoiled tubing/toolstring into the well head/well through the lubricatorpipe 13, which then is connected at its lower position below theinjector module 12 to the coupling device 21 of the upper well barrierpackage 11 b.

The fixed stripper/packer element 29 is dismounted from the lubricatorpipe 13, preferably on the vessel, when tools have to be inserted orexchanged; The upper part of the lubricator package 6 may also beprovided with a ball valve 33 if the coiled tubing has to be cut(cutting ball valve).

FIGS. 6 a-f schematically show by way of example the main operationsteps of the method being performed of the inventive assembly forinjecting the coiled tubing 7 and the tool/toolstring 32 in a subseawell 3 via a horizontal Christmas tree 9. Said tree is of a usual typehaving a production passage and an annulus passage with associatedvalves respectively. The assembly comprises the lower well barrierpackage 11 a, the injector package (with the upper well barrier module11 b), and the lubricator package 5. The upper well barrier package 11 bcomprises a so-called dual stripper BOP 22 (here as a stripper secondaryprimary and a stripper backup element. The lower well barrier package 11a, comprises a so called tripple BOP. The tripple BOP includes (seenfrom the top downwardly) a gate valve 34, a shear ram, and a pipe ram.The gate valve 34 is an isolation valve to open and close the access tothe well for each tool run in and out of the wellhead/well. The shearram is used for cutting off tools or coiled tubing. The pipe ram is avalve for sealing around the coiled tubing and is used to grip aroundit, preventing the tool(s) from falling downwardly in the well, if thecoiled tubing suspending the tool(s) has to be cut. It should be notedthat additional such valves may be present and arranged in another orderthan the ones mentioned above. Furthermore, the lower well barrierpackage 11 a may have connection for flexible hoses/pipes up to thesurface for so-called well return or killing purposes. The well iscompleted by a production tubing having a downhole safety valve 35, inaccordance with standard practice.

Before starting the intervention operation the cap of the Christmas tree9 is removed. During normal production the tree cap having a crown pluglocated in its internal serves as an outer, secondary barrier of theChristmas tree 9. All of the valves in the Christmas tree 9 are, or willthereby be closed. According to one embodiment of the invention, thelower well barrier package 11 a and the injector package 5 will beskidded into the derrick and stacked up as a unit (see FIG. 1). Theumbilical is connected to the unit, and after complete testing of theunit it is lowered down to the Christmas tree 9 by means of a runningtool. After landing of the unit on the Christmas tree it will beattached and locked thereto, via an adapter 10 that may be included inthe unit as well, and tested. According to another preferred embodiment,the packages 5, 6, 10 and 11 a may also be run down and installed asseparate units or in any suitable combined combination, e.g. the lowerwell barrier package 11 a may be a part of the Christmas tree adapter10. Thereafter, the coiled tubing lubricator package 6 will be skiddedinto the derrick and lowered down into the moon-pool of the vessel 1.The tool string 32 will then be made up, lowered into the lubricatorpipe 13 and hanged off in a frame. The coiled tubing surface injector 38will be skidded into the derrick and the coiled tubing connected to thetoolstring by means of the coiled tubing connector 31 (as shown in FIG.5) The coiled tubing upper section 16 will then be fitted to thelubricator pipe 13 and the lubricator package is ready to be lowereddown to the seabed. The lowering is executed by feeding out tubing bymeans of the surface injector 38. After landing the lubricator package 6on the injector package, they will be hydraulically locked together andtested so as to complete the installation of the well assembly 2.

FIG. 6 a shows the starting position of the intervention operation withthe lower end of the coiled tubing 7, located at the upper part of thelubricator package 6, suspending the toolstring 32 inside the lubricatorpipe 13. The moveable main stripper/packer element 30 will be activatedso as to seal around the coiled tubing 7 during its movement togetherwith the assembled tool 32 down through the lubricator pipe 13. As shownin FIG. 6 a, the main stripper/packer element 30 comprises an upper partand a lower part. The (outside) upper part will act as a pipe plug forpumping the main stripper element 30 down through the lubricator pipe.The (outside) lower part is for connecting and sealing the lubricatorpipe 13 in its lower position (see FIG. 6 d). The driving elements 17,18 of the injector module 12 are separated enough by operating themsideways to an outer position for permitting the lubricator pipe element13 to be run down through the injector module 12.

In FIG. 6 b, the lubricator pipe 13 has been run down through theinjector module 12, and a connector device arranged at the lower end ofthe lubricator pipe has entered into the multiconnector 20 of the upperwell barrier package 11 b. Said multiconnector 20 is arranged at theinterface section of the lubricator package 6 and the injector package5. The movement of the lubricator pipe 13 is accomplished by theoperation of a mechanical screw device (not shown) fitted inside aframework as schematically indicated above the injector package 5. Themulticonnector 21 is seated onto the stripper BOP 22 of the upper wellbarrier package 11 b. The connector device of the 5 lubricator pipe 13is then connected/locked to the corresponding connector device of themulticonnector 21 on top of the stripper BOP 22. A complete pressuretest of the assembly will now be performed in order to equalize thepressure with the well pressure, and the gate valve is opened.

After said pressure testing, the valves of the Christmas tree 9 will beopened. The above mentioned Christmas tree adapter 10 here comprisespassages for supply of hydraulic fluid into the valves in the tree 9,whereby these may be opened and closed during the intervention process.In FIG. 6 c, a pressure medium is introduced into the lubricator pipevia valve 36 above the main stripper element 30, resulting in that saidelement 30 and tool 32 being forced down through the lubricator pipe 13towards the multiconnector 21 of the upper well barrier package 11 b.

In FIG. 6 d the coupling device of the main stripper element 30 has beenentered into engagement with the corresponding coupling device of themulticonnector 21. The main stripper element 30 is locked and tested,and the stripper/packer of said element is activated. Thereby thelubricator pipe 13, the fixed stripper/packer element 29, and the mainstripper/packer element 30 works as a tubular locking chamber via whichsaid coiled tubing is to be run down into the well head and well. Oncethe tool 32 is introduced into the well head 4, the pressure above themain stripper element in the lubricator pipe is bled off in order tocheck the multiconnector 21 and coiled tubing 7. The lubricator pipe 13will then be flushed/cleaned from well fluid and contamination that hasentered therein during the operation.

The coupling of the lubricator pipe 13 is then released and thelubricator pipe 13 is running to an upper position, as shown in FIG. 6e, above the injector module 12 by means of the mechanical screw deviceand/or activation of the pressure medium in the space 26 (see FIG. 4) ofa cylinder device 25 (in case such a device is used) and/or the drivingelements 17, 18 of injector module 12.

As shown in FIG. 6 f the lubricator pipe 13 has been positioned abovethe injector module 12. The downhole safety valve 35 will now be openedand the coiled tubing injector module 12 starts to operate. The drivingelements 17, 18 of the injector module 12 are thus moved into engagementwith the coiled tubing 7 and the injecting operation is started forinjecting the coiled tubing and the tool down into the well head andwell.

For the removal of the coiled tubing 7 and the tool 32 out of the well,the steps described above are performed in the reverse order. Here thedriving elements 17, 18 are used to pull the coiled tubing 7 and thetool 32 out of the well until it is withdrawn up to the mainstripper/packer element 30. The driving elements 17, 18 are then movedaside and the lubricator pipe 13 is forwarded and locked to themulticonnector 21 in its lower positions and pressurised. The mainstripper/packer element and the tool are then run up through thelubricator pipe, and the valves of the well barrier package can beclosed. The pressure in the lubricator pipe is drained and the pipe isflushed clean from well fluid and so on.

The coiled tubing (or wireline) 7 is connected to the floating vessel 1and is freely extending in the water with constant tension between thevessel 1 and the injector module 12. The inventive well assemblycomprises means 37 for controlling an intake of the coiled tubing 7 tothe vessel and means for a corresponding feeding out of the coiledtubing from the vessel. The vessel 1, injector package 5 and the coiledtubing 7 extending between them form a passive system that permitssubstantial movement of the vessel 1 in relation to the well head 4,which thereby e.g. reduces the time to position/prepare the vessel forintervention of the subsea well. This is, of course, neverthelessimportant with regard to the crude conditions that often may prevailoff-shore. Other advantages with the assembly according to the inventionare reduced rigging time and thereby reduced costs for subseainterventions. The inventive assembly makes it also possible to handlecoiled tubing of greater length. Further, it does not require anchorhandling, which is difficult especially in areas with large populatedseabed.

The assembly is suitable for all kind of water depth applications, i.e.for shallow, medium as well as for deep water applications. Subseaintervention operations with the inventive assembly are typicallyperformed at water depths in the interval 800 to 3000 m.

It should be realised that the invention has been shown by way ofexample by means of the above described embodiments. A number ofalternative embodiments will therefore be obvious for a person skilledin the art without going beyond the scope of the invention as defined inthe appended claims supported by the description and the annexeddrawings.

1. A well assembly for intervention of a subsea well or a well head bymeans of a wireline or a coiled tubing connected to a tool or atoolstring, comprising lubricator means and an injector package, and inwhich said injector package is adapted to inject the wireline or coiledtubing into the well or well head, said lubricator means is adapted tobe fitted in a lubricator package and define a locking chamber via whichsaid wireline or coiled tubing is to be forwarded to the well or wellhead, said lubricator means being adapted to be connected to said wellhead, said injector package, comprises an injector module, being adaptedto be fitted to said well head, and wherein the injector module isadapted to forward said lubricator means through it, when said packagesare connected to each other and to the well head, for the purpose ofinjecting said wireline or coiled tubing into the well or well head,wherein the lubricator means comprises a lubricator pipe element and anassociated moveable stripper/packer element adapted to be connected to awell barrier module on the well head.
 2. The well assembly according toclaim 1, further comprising a well barrier package, said well barrierpackage being adapted to be fitted onto said well head, said injectorpackage being adapted to be fitted onto said well barrier package, saidlubricator package being adapted to be fitted onto said injectorpackage, and wherein the injector module is adapted to forward saidlubricator means through it, when said packages are connected to eachother respectively and to the well head.
 3. The well assembly accordingto claim 1, wherein is provided with a separate, preferablyself-standing, injector module through which of the lubricator means isforwarded.
 4. The well assembly according to claim 1, wherein theinjector module for forwarding the lubricator means through it also isadapted to inject the wireline or coiled tubing into the well or wellhead.
 5. The well assembly according to claim 1, wherein the lubricatorpackage comprises a hydraulic cylinder device for forwarding andretracting the lubricator means through the injector module between anupper position above the injector module and a lower position below theinjector module.
 6. The well assembly according to claim 1, wherein thelubricator package comprises a mechanical screw device, preferablyhydraulically operated, for forwarding and retracting the lubricatormeans through the injector module between an upper position above theinjector module and a lower position below the injector module.
 7. Thewell assembly according to claim 1, wherein the well barrier packagecomprises an upper well barrier module arranged below the injectorpackage, preferably being a part of the injector package.
 8. The wellassembly according to claim 7, wherein the well barrier package alsocomprises a lower well barrier module or package arranged below theupper well barrier module.
 9. The well assembly according to claim 1,further comprising a remote-controlled coupling device preferablyarranged in the interface section between the lubricator package and theinjector package, for connecting/disconnecting the lubricator means atits upper position, and a corresponding coupling device, preferablyarranged in the upper well barrier module for connecting/disconnectingthe lubricator means at its lower position.
 10. The well assemblyaccording to claim 1, wherein the injector module comprises at least twodriving elements by means of and between which the coiled tubing afterthe retraction of the lubricator means through the injector module isinjected into the well or well head the spacing between said drivingelements being adjustable so as to engage the driving elements and thecoiled tubing during the injecting operation of the injector module. 11.The well assembly according to claim 1, wherein the lubricator meanscomprises a lubricator pipe element, a fixed stripper/packer elementthat is arranged in the upper part or end of the lubricator pipeelement, and an associated moveable stripper/packer element.
 12. Thewell assembly according to claim 11, wherein the moveablestripper/packer element is adapted to feed and retract the coiled tubingtogether with the tool assembly or toolstring through the lubricatorpipe element.
 13. The well assembly according to claim 11, wherein eachone of the fixed stripper/packer element and the moveablestripper/packer element is sealingly arranged around the coiled tubingand between itself and the lubricator pipe element.
 14. The wellassembly according to claim
 11. wherein said moveable stripper/packerelement is adapted to be placed and preferably locked either in an upperposition above the injector module by means of coupling device, or tothe well barrier module in a lower position below the injector module bymeans of the coupling device.
 15. The well assembly according to claim14, wherein the moveable stripper/packer element remains in place at andpreferably locked to the coupling device of the well barrier modulewhile the lubricator pipe element is retracted to said upper position.16. The well assembly according to claim 1, wherein the coiled tubing isconnected to a floating vessel that comprises means including a surfaceinjector and an associated coiled tubing reel for feeding out the coiledtubing from the vessel and for retracting the same to the vessel. 17.The well assembly according to claim 16, the coiled tubing is freelyextending in the water with a tension defined by the system between thesurface injector and the injector module.
 18. The well assemblyaccording to claim 1, wherein the vessel, injector package and thewireline or coiled tubing extending between them form a passive systemthat permits substantial movement of the vessel in relation to the wellhead.
 19. A method for injecting a wireline or coiled tubing into asubsea well or well head, the method comprising: connecting an injectorpackage, comprising an injector module for injecting the wireline orcoiled tubing into the well or wellhead, to the well head, forwardinglubricator means adapted to be fitted in a lubricator package, throughthe injector module when said packages are connected to each other andthe well head, said lubricator means comprising a lubricator pipeelement and an associated moveable stripper/packer element which isadapted to be connected to a well barrier module on the well head,connecting said lubricator means defining a locking chamber via whichthe coiled tubing is forwarded to the well or well head, to the wellhead, connecting the moveable stripper/packer element to said wellbarrier module retracting the lubricator pipe element through theinjector module, and injecting said wireline or coiled tubing by meansof the injector module into the well or well head.
 20. The methodaccording to claim 19, wherein a well barrier package is connected ontothe well head, said injector package is connected onto the well barrierpackage, said lubricator package is connected onto the injector package,and wherein said lubricator means is forwarded through the injectormodule when said packages are connected to each other and to the wellhead.
 21. The method according to claim 20, wherein the wireline orcoiled tubing is forwarded through the lubricator means and connected tothe well head when the lubricator means has been connected to the wellbarrier package.
 22. The method according to claim 21, wherein, when thecoiled tubing has been connected to the well head, the lubricator meansis disconnected from the well barrier package and retracted through theinjection module such that it is displaced in relation thereto.
 23. Themethod according to claim 22, wherein, when the lubricator means hasbeen retracted, the injector module is used for injecting the coiledtubing by means of driving elements into the well.
 24. The methodaccording to claim 19, wherein the injector module is also used forretracting the coiled tubing out of the well.
 25. The method accordingto claim 20, wherein is forwarded from its retracted position andconnected to the well barrier package before the coiled tubing isdisconnected from the well head.
 26. The method according to claim 19,wherein the coiled tubing and the lubricator package are removed ordisconnected as one single unit or separately from the injector package.27. The method according to clami 19, wherein the coiled tubing isarranged with a tension defined by the system, extending from a surfaceinjector to the injector module.